With the advent of the information age, the importance of electronic devices in the industry or daily life is gradually on the rise. Accordingly, the amount of information transmitted and received through electronic devices also increases. Electronic devices may use various technologies for transmission and reception of information. For example, electronic devices may transmit and receive information through communication using light, i.e., optical communication.
Optical communication may refer to a communication method in which transmission and reception of information is performed through optical signals. When using optical communication, electronic devices may convert an optical signal into an electrical signal, thereby finally acquiring the information included in the optical signal. Meanwhile, for optical communication, optical fibers for transmitting and receiving optical signals are required. The optical fibers may include fibrous waveguides for transmitting light. Waveguides on chips (semiconductor chips, or microchips) may be made of materials which allow high-speed communication, for example, silicon which is a material causing little interference. In this case, since silicon is an indirect band-gap material, it may have low luminous efficiency which results in restricting the efficiency of light sources or photodetectors. Accordingly, in order to improve the luminous efficiency, a heterojunction with a direct band-gap material may be required. Heterojunction may be performed by various methods. For example, heterojunction may be performed by partially growing a direct band-gap material on an indirect band-gap material. Because of large mismatches in lattice constants and thermal expansion coefficients between multiple semiconductor materials, the heterojunction would require a lot of time and high costs for large-area epitaxial growth.